RESUMEN
Three experiments (Exp) were conducted to delineate a suitable model for inducing conditions mimicking physiological stress with minimal bird handling. For Exp 1, Ross x Ross 308 male chicks were fed a control diet or a diet containing 5 mg of corticosterone (CS)/kg from d 1 to 7. For Exp 2, Ross x Ross 508 broilers received 1 of 4 dietary treatments: control; control + 4 IU/kg of BW of adrenocorticotropin (ACTH)/d i.m. from d 21 to 27; control + 8 IU/kg of BW of ACTH/d i.m. from d 21 to 27; or control + 15 mg of CS/kg of diet for 14 d from 21 to 35 d of age. In Exp 3, Ross x Ross 308 broilers were fed high or low nutrient density (ND) from 1 to 41 d of age, and 0 or 20 mg of CS/kg of diet from 18 to 21 d of age. Performance parameters (BW gain, feed intake, feed conversion, and mortality) were measured in all 3 experiments. In Exp 1, CS administration significantly decreased BW gain and decreased feed intake and mortality. In Exp 2, although ACTH injection resulted in significantly depressed performance responses relative to the control, CS administration yielded significantly stronger results. In Exp 3, ND and CS interacted (P = 0.04) to affect feed intake from d 0 to 34. Broilers fed diets containing high ND and CS had higher feed intake than broilers fed low ND and CS. From 0 to 21 and 0 to 42 d, CS decreased feed intake. Increased dietary ND improved BW gain and feed conversion in Exp 3. Also, CS decreased and increased BW gain and feed conversion, respectively, during all periods in Exp 3. Dietary addition of CS negatively impacted performance of broilers, and increasing dietary amino acid density did not ameliorate these effects.
Asunto(s)
Hormona Adrenocorticotrópica/farmacología , Pollos/fisiología , Corticosterona/farmacología , Enfermedades de las Aves de Corral/inducido químicamente , Estrés Fisiológico/veterinaria , Hormona Adrenocorticotrópica/administración & dosificación , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Corticosterona/administración & dosificación , Dieta/veterinaria , Masculino , Modelos Biológicos , Estrés Fisiológico/inducido químicamenteRESUMEN
Two experiments (Exp.) were conducted to establish amino acid (AA) digestibility coefficients (DC) for broilers given corticosterone (CS)-induced stress using the apparent ileal digestibility assay. For Exp. 1, 192 Ross x Ross 708 male broilers were placed into 16 floor pens (12 birds/pen). For Exp. 2, 120 Ross x Ross 308 male broilers were placed into 10 floor pens (12 birds/pen). Pens contained nipple drinkers, pan feeders, and soft-wood shavings. Both experiments were completely randomized designs using pen as the experimental unit. In both experiments, chicks were given a common starter diet from d 1 to 20. From d 21 to 30, broilers were provided a control diet or the control + 15 mg of CS/kg of diet dissolved in soybean oil (8 and 5 replications/treatment in Exp. 1 and 2, respectively). Diets were based on corn (65.07%) and soybean meal (26.36%) and contained an indigestible marker (chromic oxide 0.3%). Diets were formulated to contain 3,175 kcal of ME, 18.5% CP, 0.79% digestible TSAA, and 1.00% digestible Lys. Stress validation was accomplished by measuring BW gain, feed intake, and liver weight on d 30. Evidence that stress occurred was apparent due to the fact that broilers fed CS had lower BW gain and higher liver weight than those fed control. On d 30, the ileal contents were removed from 3 birds/pen, pooled, dried, and analyzed for AA content. Amino acid DC were calculated using the following equation: DC = 100 -(dietary marker % x ileal AA %) / (ileal marker % x dietary AA %) x 100. Amino acid digestibility did not differ (P > 0.05) between treatments in either experiment. Based on this research, future research should be directed at establishing DC for other nutrients in stressed broilers or the effect of different nutrients on the stress response.
Asunto(s)
Aminoácidos/metabolismo , Pollos/fisiología , Corticosterona/farmacología , Digestión/efectos de los fármacos , Estrés Fisiológico/inducido químicamente , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Digestión/fisiología , Íleon/efectos de los fármacos , Íleon/fisiología , MasculinoRESUMEN
This research was conducted to evaluate immunity (experiments 1 to 3), cardiac function, and ascities resistance (experiment 4) of progeny chicks from broiler breeders fed diets differing in trace metal level and source. Broiler breeders received a control diet (75 mg of Zn and 83 mg of Mn added/kg of diet), the control diet supplemented with inorganic Zn (75 mg/kg of diet) and Mn (80 mg/kg of diet), the control diet supplemented with organic Zn (75 mg/kg of diet) and inorganic Mn (80 mg/kg of diet), or the control diet supplemented with organic Zn (75 mg/kg of diet) and Mn (80 mg/kg of diet) in experiments 1, 2, and 3. In experiment 4, the control diet and diet supplemented with organic sources of Zn and Mn were fed to broiler breeders. Immune organ weights, circulating granulocytes vs. agranulocytes, CD4 and CD8 positive T cells, cutaneous basophil hypersensitivity, and antibody titers to SRBC and breeder vaccinations were measured in progeny. Some supplemental mineral treatments increased (P < or = 0.05) cutaneous basophil hypersensitivity and relative bursa weight. All supplemental mineral treatments increased (P < or = 0.05) relative thymus weight. In experiment 4, electrocardiograph, pulse oximetry, heart rate, hematocrits, ventricle weights, and ascites incidence were measured in progeny reared in a cold-stress environment. The supplemental organic minerals increased (P < or = 0.05) left ventricle plus septum and total ventricular weights. Although progeny ascites incidence did not differ between breeder mineral treatments, breeders fed supplemental Zn and Mn sired progeny with improved cardiac functional capacity and some improvements in immunity.